I guess it depends on what software you are using to generate the report; some offer other options than marriage to denote a union of two people.

Just exactly what is the phrasing on the report now?

For the father you could use something like:
"xxx had a child with [mother's name] and later married yyy and has two children by her."

For the mother you could use something like:
"Had a child fathered by [father's name]."

No need to mention either a marriage or a lack thereof.